Thanks morgasm. I took an extra day off over the weekend so I could have a play, and didn't even get to plug a guitar in the front. Oh well, it's not going anywhere.
Sue's been using it though, and it really does sound amazing.
Antag (if you read this thread again), fitted with 6550's. We've swapped out the stock pre-amps for some cryo's and made some small improvements, although I think it's more down to taste than quailty. I'm really noticing the bottom end and cryo's are supposed to enhance that, but the amp has great bottom end anyway.